Beta 20...disappearing anode trick

[Hydrozoan]

Regarding the theory that a clean heat exchanger will make the anode work harder, it is likely that there is truth in this. Part of the protection in marine heat exchangers comes from a layer which is formed naturally on the surface of the copper-nickel tubes over about 8 to 12 weeks. If you are removing this layer every year through cleaning then it could mean that the anode is working harder during the re-layering period.
More information on the copper.org website here http://www.copper.org/applications/marine/cuni/txt_KME.html Hope this helps!

Depending on the strength of his brick acid (typically ca. 25-35% HCl, undiluted, IIRC!) and on how much (if any) calcium carbonate deposit was there to consume it first, the OP's cleaning regime could well remove the copper oxide layer completely, or substantially. I was unsure if that would work the anode noticeably harder, but if reforming the oxide layer takes 2-3 months I can well see why you think it could.

 

[PetiteFleur]

I have a Beta 25hp. I renew the anodes every year - not a problem but I have fitted a replacement brass plug which uses a screw-in anode, bought online - I'll add in a while when I can find it. Also tried a larger diameter anode but it didn't fit. I've only cleaned my stack after 7yrs when I had overheating.
This is the link http://www.boatpartsandspares.co.uk/beta-21-c.asp

 

[vyv_cox]

Depending on the strength of his brick acid (typically ca. 25-35% HCl, undiluted, IIRC!) and on how much (if any) calcium carbonate deposit was there to consume it first, the OP's cleaning regime could well remove the copper oxide layer completely, or substantially. I was unsure if that would work the anode noticeably harder, but if reforming the oxide layer takes 2-3 months I can well see why you think it could.

I understood from an earlier post that the tubes are made of copper-nickel, presumably 90/10? In that case the surface layer is not copper oxide but a highly protective film that is resistant to attack from most chemicals, although not quite so good with sulphides, not an issue here. However, since copper-nickels are highly resistant to fouling it seems unnecessary to dunk the heat exchanger in acid every year although this process probably does no harm.

 

[alahol2]

This is the link http://www.boatpartsandspares.co.uk/beta-21-c.asp

As mentioned earlier, this is the cheapest source I've found... http://www.zincsmart.com/ The website is **** but click on 'Engine/pencil anodes' on the left, then 'zinc pencil' in the middle. You want CME-0Z if you don't mind sawing a bit off the end or CME-0Z/20 if you want to pay someone to do it for you.
Service is very good.

 

[Hydrozoan]

I understood from an earlier post that the tubes are made of copper-nickel, presumably 90/10? In that case the surface layer is not copper oxide but a highly protective film that is resistant to attack from most chemicals, although not quite so good with sulphides, not an issue here. However, since copper-nickels are highly resistant to fouling it seems unnecessary to dunk the heat exchanger in acid every year although this process probably does no harm.

The Copper Development Association Inc. http://www.copper.org/applications/marine/cuni/txt_swater_corrosion_resistance.html#cor1 states that "The seawater corrosion resistance offered by copper-nickel alloys results from the formation of a thin, adherent, protective surface film which forms naturally and quickly upon exposure to clean seawater. The film is complex and predominantly comprises of cuprous oxide [my bold], often containing nickel and iron oxide, cuprous hydroxychloride and cupric oxide".

I understand that the protective film may not be just copper oxide(s). I referred to that to distinguish, simply, a likely surface film conferring protection, from on the other hand 'slime', which had been suggested in earlier posts as perhaps being the protective film being removed by cleaning. But I would not expect any of the above compounds (cuprous oxide, nickel and iron oxide, cuprous hydroxychloride and cupric oxide) or combinations thereof in a thin film to be particularly resistant to ca. 10 Molar HCl, which is what I believe brick acid typically to be.

I note your ‘... probably does no harm’, and I may be missing something - but I won’t be popping my tubestack in strong acid anytime soon. As you say, unless there's a special reason to do so it is unnecessary.

 

[Matata]

Sorry for not getting back to you. Dropped my lap top......smashed!!! Anyway this year after all the chat above I'll give it a super quick dunk in acid and a copius wash with fresh water. Its left in the air for the winter before assembling in spring. The cooling works so well with it clean stack and I can live with a wasting anode. Ta for the advice